I don’t think this is a necessity to have in a unit and have directed her to none other than google to purchase drain plugs if they absolutely needed to keep the sink water in the sink. 

Eventually, replacement is a necessity though.

Their insights highlight the necessity for a careful approach to vapor barriers and insulation, emphasizing compatibility with the building's original design and moisture management needs.Here's the plan:Ceilings/Attic Floors: Elevate insulation to R-38 or above, incorporating vapor retarder paint or smart vapor retarders for optimal moisture management.Walls: Boost insulation to R-13 or more, utilizing smart vapor retarders or materials with adjustable permeability.Basements, Crawl Spaces: Increase insulation to R-19, targeting ground moisture and internal humidity control.Materials: Opt for eco-friendly, breathable insulation and vapor barrier materials that preserve the building's historic charm.This meticulous approach elevates the property's energy efficiency and moisture management, enhancing its value and ensuring a profitable return without compromising its architectural integrity.I'd like to hear your thoughts, experiences, or any advice you might have on integrating vapor barriers and insulation in renovating historic properties.

It sounds like you moved not out of desire but out of necessity.

The deal was born from necessity.

Layoffs and mergers by necessity are happening almost every day.

It was born from necessity.

However, for further clarification, if I were to subscribe to CoStar, assuming a membership fee, would it negate the necessity to directly contact the leasing broker? 

If it's not food, transportation, housing, or ABSOLUTE necessities, don't spend money on it.

Given the condition and mentions it seems safe to assume this unit is at least 20yrs old if not older, and now well into necessity of cap-x cycle of reaping.